Coated resilient diaphragm in a fluid mirror

ABSTRACT

A day-night mirror containing a fluid light-controlling medium in an enclosure defined in part by a flexible elastomeric diaphragm. A flexible metal foil covers a major portion of at least one side of the diaphragm for substantially limiting the loss of fluid by permeation.

(Db-Ol-Yl u luwu Dulles ralenl Inventor George E. Platter, .I r.Southtield. Mich.

Mar. 28, I969 June 1, 1971 Chrysler Corporation Highland Park, Mich.

App]. No. Filed Patented Assignee COATED RESILIENT DIAPHRAGM IN A FLUIDMIRROR 9 Claims, 5 Drawing Figs.

US. Cl 350/279, 350/267 Int. Cl 602!) 5/08, G02b 7/18 Field of Search350/276,

[56] References Cited UNITED STATES PATENTS 3,001 ,l96 9/196] Mcllroy etal. 350/295X 3,054,328 9/1962 Rodgers 350/295 3,198,070 8/1965 Platzeret al. 350/278X 3,233.5 l5 2/1966 Platzer et al. 350/267 PrimaryExaminer-John K. Corbin Attorney-Harness, Talburtt and Baldwin ABSTRACT:A day-night mirror containing a fluid light-controlling medium in anenclosure defined in part by a flexible elastomeric diaphragm. Aflexible metal foil covers a major portion of at least one side of thediaphragm for substantially limiting the loss of fluid by permeation.

PATENTEDJUN Han 35821186 SHEET 2 UF 3 PATENTED JUN nan 35 2135 sum 3 ura EACKGROUND OF THE INVENTION The present invention relates generally tofluid mirrors which are minors containing a fluid light-controllingmedium. It especially relates to improvements in a day-night rear viewmirror of the type disclosed in U.S. PAT. No 3,198,070 which issued toG. E. Platzer, Jr. and L. P. Gau on Aug. 3, i965, and in U.S. Pat. No.3,233,515 which issued to G. E. Platzer, Jr., D. M. Teague and H. G.Ross, Jr. on Feb. 8, I966. These mirrors generally comprise an enclosureincluding a transparent window and a mirror or other suitable reflectorelement or means movable relative to the window. The fluid, contained inthe enclosure moves between the window and reflector to provide anopaque screen which inhibits light reflections from the reflector undercertain conditions of operation. In the absence of the fluid a brightreflection is obtained. The theory and manner of operation is completelydescribed in the referenced patents. In brief, the reflector in thefluid mirror has two positions, a day or bright position and a night ordim position.

In the day position the reflector is positioned essentially flushagainst the window with no fluid or only a thin film of fluidtherebetween. In this position, incident light is reflected primarily atthe outside surface of the window, and at the reflector. The reflectionat the second surface of the window is normally negligible because theindices of reflection of, the window material and the fluid arepreferably nearly the same. The intensity of the reflected light in thisposition is quite high since the reflector has a relatively highreflectivity, preferably on the order of about 80percent.

In the night position, the reflector is moved to a position away fromthe window; the space provided therebetween fills with the opaque fluid.In this position, incident light is reflected primarily from the frontsurface of the window. The amount reflected from the reflector elementis essentially eliminated due to the presence of the opaque fluidthrough which the light must pass twice; the first time to reach thereflector, the second time to leave it. As a result, the overallintensity of the light reflected from the reflector is reduced below thethreshold of visibility leaving essentially only that light which isreflected by the window. Thus, a dim image exists in the night positiondue to the decrease in the amount of reflected light.

In the referenced patents there is disclosed, among other forms of fluidmirrors, one which provides an enclosure including a transparent glassplate forming a window for one side of the enclosure (referred to hereinas the forward side) and a diaphragm type of fluid-retaining wall forthe other side of the enclosure (referred to herein as the rearwardside). The diaphragm is preferably made of a resilient, preferablyelastomeric material and seals the rearward side of the enclo sure. Itmust be flexible in order to allow for movement of the mirror to whichit may be attached and to serve as a means for accommodating changes involume of the fluid medium caused by changes in temperature.

This structure, while novel in its character, has been found to presenta problem of fluid loss due to permeation through the diaphragm. Theproblem has remained despite the fact that many difierent types ofdiaphragm materials have been tested in attempting to find animpermeable one.

SUMMARY OF THE INVENTION The present invention eliminates the foregoingproblem of fluid loss by placing a flexible substantially impermeablecoating or layer over a major part ofthe surface area of at least oneside ofthe diaphragm.

Accordingly, a principal object of the present invention is to provide afluid mirror containing a composite diaphragm structure which issubstantially impermeable to the fluid thereby preventing its loss.Other objects and advantages of the invention will be apparent from thefollowing description and the drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. I is a side elevational view of anadjustable rear view mirror in its day position and embodying thefeatures of the invention, the mirror assembly being shown in sectionand the support therefor partly in elevation and partly in section tomore clearly show the invention.

FIG. 2 is an end view and section taken at 2 2 of FIG. I.

FIG 3 is an enlarged edge portion of the mirror assembly shown in FIG.I.

FIGS. 4 and 5 are sectional views of an edge portion of the structure ofFIG. 1 showing modified forms of the sealing structure between thediaphragm and mirror housing and also the connection between thediaphragm and the reflector.

BRIEF DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIGS. 1, 2and 3, numeral 10 generally designates a side-mounting type adjustablerear view mirror provided with a mounting bracket 11. Secured to head 12of bracket 11 by screws 13 is a housing 14 with a wall 16 surroundingthe mirror assembly, generally designated 22, to protect it from theweather. Mirror assembly 22 is preferably pivotally supported on aspherical headed hollow sleeve 24 which is slidably mounted in a cableguide and control mount 26. The latter comprises an enlarged headportion 28 having a tapered stem 32 extending rearwardly into brackethead 12 and secured in a complementary shaped bore 34 by screw 36. Headportion 28 is provided with rearwardly extending cablereceiving bosses38 at three equally spaced angular positions around the circumference ofthe flange to provide threaded recesses 40 in which coiled sheathing 41of cables 42, 44 and 46 is threaded. These cables connect, as seen inFIG. 2, at corresponding positions to mirror assembly 22 for providingswivel adjustment. Spherical headed sleeve 24 is biased forwardly,preferably by a conical compression spring 48, so as to seat in bearingdepression 50 provided in an outward or rearward extending projection 52of support plate 54. An opposite balanced force is furnished assembly 22by mirror adjustment cables 42, 44 and 46 which operate in flexibletubes or sheaths 41 and are constantly under tension. The mirroradjustment cables are connected to a manual control means (not shown).Specific details of a suitable three-wire control such as herecontemplated for making angular mirror adjustments are referenced in US.Pat. No. 3,233,515.

Mirror assembly 22 comprises, in addition to support plate 54, acircular window 60, a circular metal frame 62 of L-section, and aflexible diaphragm 64, the last three named parts forming an enclosurefor receiving a movable mirror element or other suitable reflector meansgenerally designated by numeral 66 and providing a fluid chamber 68 forreceiving an opaque fluid 70 which may be of the type described in thereferenced patents. Window 60 preferably comprises a plate of cleartransparent glass. Reflector 66 may likewise be a glass plate providedwith a mirrored surface 72. Mirrored surface 72 is clearly visiblethrough window 60 and acts as the reflecting surface for the mirror whenin the bright or day position as shown in FIG. l wherein reflector 66 ispositioned against the stops or indexing means 76.

It will be noted that reflector 66 has a predetermined diameter, whichis less than the inside diameter of annular portion 78 of frame 62,providing an annular gap 80 between the outer edge of the reflector 66and casing portion 78. This gap permits the free movement of the fluidbetween reflector 66 and casing 78 when reflector 66 is moved rearwardlyin chamber 68. In this operation reflector 66 will generally slide on afilm of the fluid in the bottom of the enclosure and will be supportedto some extent by diaphragm 64, of which a central portion 82 is bondedby a suitable cement to rear face 84 of reflector 66. The enclosure isof sufficient depth to permit displacement of reflector 66 rearwardly asufficient distance to satisfy the optical conditions required of themirror when in the night position. That is, a layer of fluid must beprovided between the reflector and window which substantially inhibitsthe reflection of light from mirrored surface 72 when in the rearward ornight position. As described in the patents aforesaid, a movement in theorder of about 0.125 inch has been found sufficient with the particularfluid medium described therein.

Diaphragm 64 is a resilient material, preferably an elastomeric one suchas a nitrile rubberlike synthetic acrylonitrile butadiene copolymer(commonly known as Buna-N), a butyl rubber, polyurethane rubber,silicone rubber or the like. Natural rubbers are also acceptable. Animpervious flexible coating 65 is placed over a substantial part of thesurface area of at least one side of diaphragm 64 as shown in theFigures. This coating preferably takes the form of an aluminum foil forexample and may be bonded to diaphragm 64 by means ofa suitableadhesive.

If the diaphragm material is the preferred acrylonitrile butadienecopolymer, alodized aluminum foil may be readily bonded thereto withChemlok 205 which is an adhesive mar. keted by the Hughson ChemicalCompany of Erie, Pa. This material is a mixture of polymers, organiccompounds and mineral fillers in a methyl isobutyl ketone solventsystem. it is gray in color and has a solids content of 2226 percent, aspecific gravity of 0.92-0.94 at 72 F., a flashpoint of 80 F. (Tayliabueopen cup) and a viscosity of I 1 30 cps. (Brookfield Model LUF, 02Spindle, 30 r.p.m., 72 F.). Satisfactory bonds between these materialshave been obtained by applying a layer of Chemlok 205 to the diaphragm,laying a 0.0015- inch thick piece of aluminum foil over the adhesive,pressing the diaphragm and foil together and heating at an elevatedtemperature until cured.

Other adhesives such as cyanoacrylate a contact adhesive marketed byEastman Kodak and known as Eastman 910, may also be used. The particularbonding agent will depend on the diaphragm and foil materials which areused. The examples described above are provided to more clearlyillustrate the invention and are not intended to restrict it or limit itother than as claimed.

Bonding the foil to the rearward side of diaphragm 64 as shown at 65 inFIG. 1 provides a flexible yet impermeable composite. Coating 65 may bebonded to the forward or interior side of diaphragm 64 also. A coatingon either side has distinct advantages. It should preferably at leastcarry a coating on the inner surface where it additionally may serve toprevent any chemical reaction between the diaphragm and the fluid,particularly when the diaphragm is a rubber or elastomer. It may also becarried on the rearward side to prevent any possible oxidationdegradation of the diaphragm material. The diaphragm may carry a coatingon both sides if desired.

Diaphragm 64 may be ofa generally shallow pan shape having a base orbody portion 88, an outer rim 90 provided with an inturned lip or flange92 spaced from body portion 88 the depth of frame 78 such that it snuglyembraces and fits the frame. A central portion 82 of diaphragm 64projects forwardly of the body portion. The central portion is bonded torear face 84 and is connected to the body portion by a conical web 94.Lip 92 of diaphragm 64 is also preferably provided with a raised bead 96preferably of semicircular section which may be abutted by window 60 toform a fluid seal between it and the window. Support plate 54, whoseperiphery conforms to the periphery of angular portion 78 of frame 62and diaphragm 64, is held in abutment thereto by retaining ring 98 whichalso holds window 60 against sealing bead 96 of the diaphragm. In thisconnection it will be noted that retainer 98 has a forward inwardlysloping flange 100 which abuts a complementary shaped chamfered edge 102of window 60 and at the opposite end is formed with a plurality of tabs104 (see HO. 2) spaced circumferentially of the retaining ring. The tabsare bent against support plate 54 adjacent its periphery to hold theentire mirror assembly 22 together while simultaneously placing bead 96and the opposite end of the diaphragm under sufiicient compression toeffect a fluid seal of the assembly.

As seen in FIGS. 1 and 2, support plate 54 is preferably provided withan outwardly pressed circular riblike portion 108 and radially outwardlypressed riblike portions 110 which connect with the outwardly pressedportion 52 previously described. Dish portion 52 not only includes abearing depression 50 for seating the spherical end of sleeve 24 of themirror mount but also provides an annular depression 112 for receivingone end of a compression spring 114 which seats over projection 50 atits outer end and has its inner end bearing against a platelike member116 suitably secured as by cementing to portion 82 of diaphragm 64. Thisarrangement normally biases reflector 66 to its forward position againststops 76. Plate 116 is preferably made of metal and formed with anoutward depression 118 in which reflector-acutating cable 120 isanchored by an enlarged head portion 122. Cable 120 extends throughopening 124 in bearing portion 50 of the support plate, passes into bore126 of sleeve 24 in which its coiled sheath 127 is threadedly secured.The cable and sheathing then extend through bracket 11 to its ultimateposition of operation, usually the dash of the vehicle. It will also benoted that support plate 54 is provided with three outward depressions130 located intermediate ribs 110 in which the mirrorpositioning cables42, 44 and 46 are anchored.

As is evident from the above description the outer face of window 60provides a reflecting surface of low reflectivity which will provide thesurface of greatest reflecting intensity in the night position ofreflector 66 when the latter is in its rearward or night position.Mirrored surface 72 of reflector 66 provides a reflecting surface ofhigh reflectivity and the reflecting surface of greatest reflectingintensity when reflector 66 is in its forward or day position. Inoperation, mirror assembly 22 may be adjusted to any angular position byoperation of cables 42, 44 and 46, there being sufficient clearancebetween the outer rim of the mirror-retaining member 98 and the wall 16of the hood 14 to permit such adjustment. Shifting between the day andnight positions, is accomplished by applying tension to cable 120 thusdrawing the reflector rearwardly for obtaining the night position andpermitting spring 114 to return reflector 66 forwardly against the stops76 for its day position.

Referring now to FIG. 4 an alternate arrangement is shown for effectinga seal between diaphragm 64, frame 62 and window 60. The figure alsoshows an alternate arrangement for connecting a mirror-actuating meansto mirror 60. In this embodiment, plate 116 is bonded directly to mirror66 and diaphragm 64 overlaps and is bonded to the back of plate 116.

FIG. 5 shows another arrangement for effecting a seal between diaphragm64, frame 62 and window 60 wherein the diaphragm is clamped betweenwindow 60 and frame 62.

It will be apparent that various changes and modifications may be madein the described construction without departing from the spirit andintent of the invention.

What 1 claim is:

I. In a fluid mirror of the type comprising;

enclosure means defined at least in part by a transparent window and aresilient diaphragm,

light-reflecting mirror and an optically dense fluid medium in theenclosure, and

means for moving the mirror toward and away from the window between dayand night positions respectively,

the improvement comprising in combination therewith a substantiallyimpermeable flexible coating covering at least the side of the diaphragminterior of the enclosure for substantially sealing it against thetransmission and loss of the fluid.

2. The mirror of claim 1 wherein the diaphragm comprises an elastomericmaterial.

3. The mirror of claim 2 wherein the coating comprises a metal foil.

4. The mirror of claim 2 wherein the coating is aluminum foil.

5. The mirror of claim 4 wherein the foil is about 0.0015 inch thick.

6. The mirror of claim 4 wherein the aluminum foil is bonded to thediaphragm by an adhesive 9. The mirror of claim 2 wherein the elastomeris Buna-N and the coating is aluminum foil.

Certificate of Correction June 1, 1971 Patent No. 3,582,186

George E. Platzer, Jr.

It is certified that error appears in the above-identified patent andthat said Letters Patent are hereby corrected as shown below.

Cancel the three sheets of drawings and insert the drawing shown below:

INVENTOR- 27 7251!!! we zeeb Signed and sealed this 16th day of May1972.

Rw M 6 mm mP o a r 6 T w E.@ E8 m m 0 0 R J E H W. T we fi M 0 W L S A8l b A EA

1. In a fluid mirror of the type comprising; enclosure means defined atleast in part by a transparent window and a resilient diaphragm,light-reflecting mirror and an optically dense fluid medium in theenclosure, and means for moving the mirror toward and away from thewindow between day and night positions respectively, the improvementcomprising in combination therewith a substantially impermeable flexiblecoating covering at least the side of the diaphragm interior of theenclosure for substantially sealing it against the transmission and lossof the fluid.
 2. The mirror of claim 1 wherein the diaphragm comprisesan elastomeric material.
 3. The mirror of claim 2 wherein the coatingcomprises a metal foil.
 4. The mirror of claim 2 wherein the coating isaluminum foil.
 5. The mirror of claim 4 wherein the foil is about 0.0015inch thick.
 6. The mirror of claim 4 wherein the aluminum foil is bondedto the diaphragm by an adhesive 7 The mirror of claim 2 wherein theelastomer is Buna-N.
 8. The mirror of claim 1 wherein the coating coversboth sides of the diaphragm.
 9. The mirror of claim 2 wherein theelastomer is Buna-N and the coating is aluminum foil.